That is why there is a small time window for smallish niches, like Elixir, Clojure or Rust. One has to have their eye one fashion, the crowds, the knowledge gap and the perceived utility.

I personally wouldn't wanting to be competing with all the other beginner material and sufficiently advanced material would take forever to produce.

But if there was a 100 page book on writing an Elixir/Phoenix app and deploying it on K8s across 4 cloud providers, using a CDN and Aerospike, I'd pay 50$ for that.